1. Field of the Invention
The present invention relates to a method of transferring print data from a host computer to a printer connected to the host. The present invention also relates to a printer controller for implementing the method, and to a computer program for executing the method.
2. Description of the Related Art
The performance of a printer can be evaluated by factors such as PPM (Print Per Minute: the number of printed sheets produced per minute) and FPT (First Print Time: the time taken for the printer to begin the first printing after the print command is issued by the user). In improving the efficiency of print operation, people often regard PPM as the more important factor than FPT because it concerns the net printing speed of the printer. For increasing the gross throughput, however, FPT is also an important factor, and should be made as short as possible.
Generally the first print time depends on the amount of print data to be transferred and the data transfer rate of the interface between the host computer and the printer. Specifically, as the amount of print data is smaller and/or the data transfer rate is higher, FPT becomes shorter. On the other hand, as the amount of print data is greater and/or the data transfer rate is lower, FPT becomes longer.
In a conventional data transfer system, the standard interface between the host and the printer is usually the centronics interface whose data transfer rate may be 100 KB/s˜200 KB/s at best. To compensate for the slowness of the transfer rate, the print data is compressed by an appropriate compression method. Accordingly, the volume of the print data is reduced, which contributes to the shortening of the net time taken for data transfer from the host to the printer. The conventional scheme, however, sometimes fails to shorten the first print time, and even prolongs it due to the additional time taken for the host to compress the print data and for the printer to decompress the transferred data.